Damper control for refrigeration systems



Sept. 16, 1969 J. E. FRISTOE ETAL 3,466,889

DAMPER CONTROL FOR REFRIGERATION SYSTEMS Filed Nov. 24, 1967 2 Sheets-Sheet 1 p 16, 1969 J. E. FRISTOE ETAL DAMPER CONTROL FOR REFRIGERATION SYSTEMS 2 Sheets-$heet 2.

Filed Nov. 24, 1967 vv. n u H 1 I 1 1 I y I 1 I. 1 I I l1 1 I I 1 !lllllllwlv I United States Patent US. Cl. 62-184 9 Claims ABSTRACT OF THE DISCLOSURE Refrigerating apparatus having a damper control responsive to discharge pressure in either of two separate refrigeration circuits. Two pneumatic cylinders are connected to a plate assembly which, upon rotation, causes the damper blades to open or close. The plate assembly will rotate in response to the higher of the discharge pressures of the two refrigerant circuits.

Background of the invention This invention relates to a damper control for refrigeration systems, and more particularly to a control for operating a damper to vary the flow of air over air cooled condensers of a two compressor refrigeration system.

In refrigeration systems comprising two separate refrigerant circuits, each circuit having its own compressor, cooler tubes and air cooled condensing apparatus or group, the condensing apparatus of all of the circuits may be located in the same area. conventionally, a common air forcing means, such as a fan, is utilized for directing air through all of the condensing groups. A single damper assembly is employed for regulating air flow over all of the condensing groups.

The damper and fan are used to regulate the air flow over the condensers so that the refrigerant pressures on the discharge side of the compressors are controlled.

Due to varying ambient temperatures and to varying refrigerant loads, the compressor discharge pressures might fluctuate excessively for one or more of the refrigerant circuits if the damper and fan control were not provided.

One method heretofore used in controlling the movement of damper blades was to connect such blades to an electric damper motor adapted to operate in response to predetermined pressures on the discharge side of one of the compressors. While an electric motor may function adequately to control the damper blade movement, the use of such a motor requires extensive electrical control circuitry to effect incremental movements of the damper blades as the refrigerant pressures vary incrementally. Moreover, if the discharge pressure of the one compressor was not excessive the damper control might be rendered ineffective.

Brief summary of the invention Briefly, the apparatus of this invention includes a plurality of damper blades adapted for conjoint movement, a blade control assembly rotatable about an axis for moving the blades, a first actuating means connected to the blade control assembly on one side of the axis of the latter for moving the assembly in response to the discharge pressure of one refrigerating system, and a second actuating means connected to the blade control assembly on the other side of the axis of the latter for moving the assembly in response to the discharge pressure of another refrigerating system.

One of the primary objects of this invention is to provide damper apparatus for controlling refrigerant pressure on the discharge side of either compressor of a two compressor refrigeration system utilizing only one condenser fan.

Another object of this invention is to provide damper apparatus for controlling the air flow over the common condensing apparatus of two refrigeration systems, the position of said damper apparatus being responsive to refrigerant pressure in such systems.

A further object of this invention is to provide apparatus of the class described which does not utilize an electrical motor for operation of the damper assembly.

Still another object of this invention is to provide damper apparatus such as described which, where the apparatus is common to two refrigeration systems, operates in response to the refrigerant pressure of the system having the higher refrigerant pressure.

Another object of this invention is to provide apparatus of the type described which is economical and eflicient in operation.

Other objects and advantages of this invention will be made apparent as the description progresses.

Brief description of the drawings In the accompanying drawings, in which one of various possible embodiments is illustrated,

FIG. 1 is a schematic view of the damper apparatus of this invention shown in connection with one form of refrigeration apparatus with which the damper apparatus may be used;

FIG. 2 is an enlarged fragmentary side elevation View of FIG. 1; and

FIG. 3 is a plan view of FIG. 2, certain parts being broken away for clarity.

Like parts are indicated by corresponding parts throughout the several views of the drawings.

Description of the preferred embodiment Referring now to the drawings, damper apparatus of this invention is shown generally at 1 in FIG. 1. As shown, the damper apparatus 1 is connected by a line 3 to a closed circuit refrigeration system essentially comprising a compressor 5, condenser coils 7, a receiver 9, a subcooling coil 11, a shut-ofli valve 13, a drier 15, a solenoid valve 17, an expansion valve 19 and a cooler 21. A refrigerant line 23 connects the discharge outlet of compressor 5 to condenser coils 7 and the latter are connected to receiver 9 by a line 25. The receiver 9 is joined to subcooling coil 11 by a line 27, and a line 29, which includes valve 13, drier 15, solenoid valve 17 and expansion valve 19, connects the coil 11 to cooler 21. Cooler 21 is connected to the suction part of compressor 5 by a line 31. Damper apparatus 1 is also connected to a second refrigeration system (not shown) and generally identical to the system described above and comprising parts 5 through 31, by a line 33. If desired, the cooler 21 could be constructed to function for both refrigerant circuits, the refrigerant inlet and outlet being designated A and B, respectively, for the second circuit.

The damper apparatus is shown on a reduced scale in FIG. 1, but it will be understood that such apparatus covers a single housing structure in which the condensing coils 7 of both refrigerant systems are located. A fan 35 is adapted to direct air over the condensing coils and through the damper assembly.

The damper assembly 1 comprises a frame 37 formed of side members 39 and end members 41. A plurality of damper blades 43 located side-by-side extend between end members 39. Blades 43 are attached to rods 45 and the ends 47 of the rods are rotatably mounted in the end members 39 to permit rotational movement of the blades.

The longitudinal edges of the blades overlap one another as indicated at 49 and the edges of the blades adjacent side members 41 overlap edge plates 51 so that the blades, in the position shown in FIG. 2, close the damper opening. The ends 47 of rods 45 at one end of the damper assembly extend through and beyond the adjacent end member 41 as indicated at 53. This end member 41 is also located a short distance inwardly from the ends of side members 39.

Control apparatus, generally indicated at 55, is provided between the ends of side members 39 and outside the end member 41 for controlling the rotational movement of rods 45 and consequently, the rotational movement of the damper blades 43.

The control apparatus includes a plurality of crank arms 57 securely connected to the end portions 53 of rods 45. The outer ends of all of the arms 57 are pivotally connected to a link 59 so that movement of the link 59 causes all of the damper blades to be rotated at the same time and the same amount.

The end portion- 53 of the center rod 45 extends through a bracket 61 overlaying the center arm 57 and link 59 and secured to end member 41. A control plate assembly 63 is attached to the outer end of the rod end portion 53 extending from bracket 61 and is held against axial movement on the rod by collars 65 and 67. Assembly 63 includes two identical plates 69 and 71 separated from one another by a spacer 73. Each plate has two elongated parallel slots 75 and 77 spaced from one another on opposite sides of the axis of rotation of the control plate assembly. The slots 75 .and 77 in plates 69 and 71 are aligned with one another. It will be seen that counterclockwise rotation of control plate assembly 63 as viewed in FIG. 2 causes rotation of the center rod 45, and consequently counterclockwise rotation of damper blades 43.

Power means 79 is provided for rotating plate assembly 63. The power means 79 includes two pneumatic cylinders 81 and 83 each of which is pivotally connected to the frame 37 by an arm 85 attached to a bracket 87 which is connected to a cover plate 89 extending between the upper edges of the ends of side member 39. The cylinders 81 and 83 are connected by lines 33, and 3, respectively, to the lines 25 of the two refrigeration systerns.

Cylinders 81 and 83 include pistons 91 and 93, respectively connected to piston rods 95 and 97, respectively extending out one end of each of the cylinders. Rods 95 and 97 are attached to links 99 and 101, respectively, which extend between the plates 69 and 71 of assembly 63. The outer end of link 99 is slidably connected to the assembly 63 by .a pin 103 extending through the slots 75 in plates 69 and 71. The outer end of link 101 is slidably connected to plate assembly 63 by a pin 105 extending through the slots 77 in plates 69 and 71. In the position shown in FIG. 2, i.e., with pin 103 being located at the bottom of slots 75 and with pin 105 being located at the top of slots 77, the damper blades are held in the closed position. A spring 107 extends between an arm 109 on plate 71 .and one bracket 87 to maintain a clockwise rotational force on the plate assembly 63. As will be made apparent, this force may be overcome by the refrigerant pressures behind the pistons 91 and 93.

Assuming the refrigerant systems are both in an inactive position and the damper blades 43 are in a closed position, operation of the apparatus is as follows:

If both refrigerant systems are placed in operation the refrigerant pressure supplied to the respective condenser groups by the respective compressors begins to rise. Assuming the loads or refrigeration requirements placed on the two systems are different, the compressor discharge pressure of the two systems will rise at different rates. If, for example, the discharge pressure from compressor shown first reaches some predetermined value, such as 180 p.s.i., for example, this pressure, which exists in line 3 and behind piston 93 in cylinder 83, causes pis ton 93 to move to the left as viewed in FIG. 2. This movement of piston 93 causes link 101 to move to the left and plate assembly begins to move in a counterclockwise direction as viewed in FIG. 2 due to the engagement of pin with the upper end of slots 77. As the plate assembly moves in such a direction due to increasing refrigerant pressure behind piston 93, the damper blades 43 begin to open as a result of the movement of the center crank arm 57, line 59 and the remaining crank arms 57.

The pin 103, which is not being forced to the right as viewed in FIG. 2 since the refrigerant pressure behind piston 91, line 33 and discharged from the compressor of the other refrigeration system is assumed to be lower than the predetermined actuating pressure, merely slides in the slots 75 as the plate assembly 63 is rotated in the counterclockwise direction by pin 105. The damper blades 43 continue to open as the refrigerant pressure behind piston 93 continues to rise, and when a predetermined compressor discharge pressure, such as 270 p.s.i., is reached, a pressure responsive switch, such as a switch 111 in line 23, for example, may be actuated to energize the motor for fan 35. The fan increases the flow of air through the condensers and the opened damper blades 43.

If the compressor 5 shown unloads or shuts off, the discharge pressure in line 3 and behind piston 93 drops and the return spring 107 causes the plate assembly 63 to move in a clockwise direction and damper blades 43 begin to close. If the discharge pressure in the other refrigerant system is above the predetermined damper actuating pressure, such as p.s.i., for example, the piston 91, rod 95, line 99 and pin 103 will be moved to the right as viewed in FIG. 2 to a point which is indicative of the particular pressure in the system. Assuming for example, that the discharge pressure in the other system is 230 p.s.i., the pin 103 will engage the ends of slots 75 before the return spring has returned the plate assembly 63 to its original position. Accordingly, the damper blades are held in a position which is determined by the discharge pressure of the other refrigerant system. The pin 105 slides in the slots 77 as it returns to its original position It will be seen that if both cylinders 81 and 83 are being supplied discharge pressure from their respective compressors, the plate assembly 63 will maintain the damper blades 43 in a position appropriate to control the higher of the two discharge pressures.

It will thus be seen that the damper apparatus will either not only allow a conventional damper function, i.e., to modulate condenser air flow in response to condenser discharge pressure, but in addition, in a dual refrigerant circuit system where one condenser fan is utilized, the apparatus will allow the system with the higher discharge pressure to override the system with the lower discharge pressure and in this manner, prevent the position of the damper blades from creating excessively high refrigerant pressure in either refrigerant system.

In view of the foregoing, it will be seen that the several objects and other advantages are obtained.

Although only one embodiment of the invention has been disclosed and described, it is apparent that other embodiments and modifications of the invention are possible within the scope of the appended claims.

We claim:

1. Damper apparatus for controlling air flow over the condensers of two separate refrigerating circuits comprising a frame, damper blades movably mounted in said frame, means connecting said blades for conjoint movement upon movement of one of said blades, means for moving said one blade comprising a blade control assembly connected to said one blade and adapted for rotary movement on an axis, a first blade control assembly actuating means connected to said assembly on one side of said axis, a second blade control assembly actuating means connected to said assembly on the other side of said axis, each of said blade control assembly actuating means being responsive to refrigerant pressure in different refrigerating circuits for rotating said blade control assembly to cause movement of said damper blades.

2. Damper apparatus as set forth in claim 1 wherein each blade control assembly actuating means includes a cylinder, a piston in said cylinder, means connecting said piston to said blade control assembly, and a conduit connecting the cylinder to one of said refrigerating circuits.

3. Damper apparatus as set forth in claim 2 wherein said blade control assembly includes at least one member having slots therein on opposite sides of said axis, each of said means connecting the pistons to said blade control assembly including an elongated member, and means connected to said elongated member and extending through one of said slots.

4. Damper apparatus as set forth in claim 2 wherein each of said means connecting the pistons to said blade control assembly comprises an elongated member slidably connected to said blade control assembly.

5. Damper apparatus as set forth in claim 1 wherein said blade control assembly includes at least one plate having elongated slots on opposite sides of said axis, said first blade control assembly actuating means including a cylinder, a piston in said cylinder, means connecting said piston to said plate, and a conduit connecting the cylinder to one of said refrigerating circuits, said means connecting said piston to said plate including an elongated member, pin means connected to said elongated member and extending through one of said slots, said second blade control assembly actuating means including a sec ond cylinder, a second piston in said second cylinder, means connecting said second piston to said plate, and a second conduit connecting said second cylinder to the other refrigerating circuit, said means connecting said second piston to said plate including a second elongated member and second pin means connected to said second elongated member and extending through the other slot, each of said pin means being adapted, when the refrigerant pressure pressure behind the piston to which the respective pin means is connected is above a predetermined value and higher than the pressure behind the other piston, to move said plate in a direction for opening said damper blades, the other pin means sliding in its slot during such plate movement.

6. Damper apparatus as set forth in claim 5 further including a return spring connected between said frame and said plate, said spring biasing said plate toward a position in which said damper blades are closed.

7. Damper apparatus as set forth in claim 1 wherein each of said blade control assembly actuating means comprises a cylinder, a piston in said cylinder, means slidably connecting said piston to said blade control assembly, a conduit connecting said cylinder to the dis charge side of one of said refrigerant circuits, and means pivotally connecting said cylinder to said frame.

8. Damper apparatus as set forth in claim 7 further including a return spring connected between said frame and said blade control assembly, said spring biasing said plate toward a position in which said damper blades are closed.

9. Damper apparatus as set forth in claim 8 wherein said blade control assembly includes at least one member having slots therein on opposite side of said axis, each of said means connecting the piston to said blade control assembly including an elongated member, and means connected to said elongated member and extending through one of said slots.

References Cited UNITED STATES PATENTS 2,958,208 11/1960 Broden 62181 3,004,402 10/1961 Dart 62l84 X 3,138,941 6/1964 Jensen 62l84 3,242,686 3/1966 Bowman 62l84 WILLIAM J. WYE, Primary Examiner US. Cl. X.R. 62507 

